When playing fills using triplets, each new beat starts with the opposite hand to the previous beat. Try playing the following example RLR LRL etc, and then LRL RLR etc. Another useful technique is to play all the notes on a particular drum with one hand, for example, RRR LLL etc.
Once you are comfortable moving around the drums and using triplets, try alternating between a basic triplet beat and a one bar fill as demonstrated here.